Rip spacing and persistence on an embayed beach
Rip spacing and persistence on an embayed beach
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内湾海滩上的裂隙间距和持久性
DOI：
10.1029/2005jc002965
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发表时间：
2006
影响因子：
--
通讯作者：
R. Ranasinghe
中科院分区：
文献类型：
--
作者：
R. Holman;G. Symonds;E. Thornton;R. Ranasinghe
[1]四年的日常时间曝光的图像，从一个陷入困境的海滩进行了检查，研究的间距，持久性和位置的偏好，在一个自然的撕裂通道系统的撕裂。在782天里，总共观察到5271条裂沟。发生率统计显示，没有证据表明，与陷入一个海湾海滩的立缘波的首选位置模式。裂缝间距的直方图，大多数模型的主要诊断观察，以及建模的对数正态分布（平均间距为178米）。然而，间距是高度沿岸变量（时间平均的标准差/沿岸平均的撕裂间距为39%），所以他们是值得怀疑的价值作为一个诊断变量。风暴驱动复位到沿岸均匀的条件下所需的大多数模型平均每年只发生四次，使rip生成模型相关的系统行为的一小部分。裂缝间距后，15个观察到的复位事件是不相关的酒吧波峰距离。324个单独的撕裂通道轨迹的寿命平均为45.6天。裂口同样移动的在两个沿岸方向，但RIP迁移率的变异系数很大，即使是高迁移率。平均迁移率与沿岸流的代理（R2为0.78）相关性良好。因此，没有明显的证据表明，该海滩上的裂流河道的形成、间距和迁移可以用现有的简单模型来解释。此外，这些模型所假设的沿岸均匀初始条件是罕见的棕榈海滩，使模型一般不适用。
[1] Four years of daily time exposure images from an embayed beach were examined to study the spacing, persistence, and location preferences of rips in a natural rip channel system. A total of 5271 rip channels was observed on 782 days. Occurrence statistics showed no evidence of the preferred location pattern associated with standing edge waves trapped in an embayed beach. The histogram of rip spacing, the primary diagnostic observable for most models, was well modeled by a lognormal distribution (mean spacing of 178 m). However, spacings were highly longshore variable (time mean of the standard deviation/longshore mean of rip spacing was 39%), so they are of questionable merit as a diagnostic variable. Storm-driven resets to the longshore uniform condition required by most models occurred only four times per year on average, making rip generation models relevant to only a small fraction of the system behavior. Rip spacings after the 15 observed reset events were uncorrelated with bar crest distance. The lifetime of the 324 individual rip channel trajectories averaged 45.6 days. Rips were equally mobile in both longshore directions, but the coefficient of variation of rip migration rates was large, even for high migration rates. The mean migration rate was well correlated to a proxy for the longshore current (R2 of 0.78). Thus there is no significant evidence that the formation, spacing, and migration of rip channels on this beach can be explained by currently existing simple models. Moreover, the alongshore uniform initial conditions assumed by these models are rare on Palm Beach, making the models generally inapplicable.